Old post I know, but for those who are curious, I have 2 megas going now, both the new and old versions. These are cheap and really effective!
The printer has a bowden extruder, has a printing dimension of 210, 210, 205mm, a printing head that moves in the X and Z direction, with the bed moving in the Y, heated bed etc.
I have been using them to print many a tile and are robust (I can move these printers without needing to relevel or setup without issue).
The prints are solid however the printers lack features like being wifi enabled (unless you set up with octoprint in a raspberry pi which is super simple) and auto levelling.
The printers can wear out quick though if you use them for long prints, like those which take days to complete, however a quick £10 fix can solve this (install a MOSFET chip for the heatbed, which is super easy and tons of tutorials out there) which will extend the lifespan, even for other printers of the same price range. The board is a Trigorilla 1.1 board (I have at least) with options for upgrades like more fans.
These printers can also print ABS as well if that takes your fancy but I stick to PLA as I would like to avoid headaches of warping (which can happen on any printer).
The printer can print at 0.05 mm layers, however you’d need a seriously level bed to do this (this is the same for any printer). But as the printer is cheap, the ultrabase that is supplied can sometimes be convex or concave in the middle, however you can return the unit or buy a new base for cheap. My original Mega is fine, but the new printer is slightly convex so causing squishes of prints in the middle, hopefully I can wear the bed in.
I will argue that the printer can perform at a level similar to the more expensive printers out there if you have the know how. However, the I3 Mega is really useful for people at any level, even for a beginner (if you are willing to make mistakes!).
You can use most slicers, but I mostly use Cura, and I have not had any issues.
I hope this is of some help to people out there, although I cannot help in any printer comparisons.